Lanthanide complex catalyst and polymerization method employing same

ABSTRACT

A novel class of lanthanide metal salen complexes can be used as an ingredient of a catalyst system. The catalyst system can be used in polymerizations of ethylenically unsaturated hydrocarbon monomers.

CROSS-REFERENCE TO RELATED APPLICATION

This is a national stage entry application of international applicationno. PCT/US2012/023909, filed 5 Feb. 2012, and claims the benefit of U.S.provisional patent application No. 61/439,862, filed 5 Feb. 2011, thedisclosure of which is incorporated herein by reference.

BACKGROUND INFORMATION

Rubber goods such as tire treads often are made from elastomericcompositions that contain one or more reinforcing materials such as, forexample, particulate carbon black and silica; see, e.g., The VanderbiltRubber Handbook, 13th ed. (1990), pp. 603-04.

Good traction and resistance to abrasion are primary considerations fortire treads; however, motor vehicle fuel efficiency concerns argue for aminimization in their rolling resistance, which correlates with areduction in hysteresis and heat build-up during operation of the tire.(A reduction in hysteresis commonly is determined by a decrease in tan δvalue at an elevated temperature, e.g., 50° or 60° C. Conversely, goodwet traction performance commonly is considered to be associated with anincrease in tan δ value at a low temperature, e.g., 0° C.)

Reduced hysteresis and traction are, to a great extent, competingconsiderations: treads made from compositions designed to provide goodroad traction usually exhibit increased rolling resistance and viceversa.

Filler(s), polymer(s), and additives typically are chosen so as toprovide an acceptable compromise or balance of these properties.Ensuring that reinforcing filler(s) are well dispersed throughout theelastomeric material(s) both enhances processability and acts to improvephysical properties. Dispersion of fillers can be improved by increasingtheir interaction with the elastomer(s), which commonly results inreductions in hysteresis (see above). Examples of efforts of this typeinclude high temperature mixing in the presence of selectively reactivepromoters, surface oxidation of compounding materials, surface grafting,and chemically modifying the polymer, typically at a terminus thereof.

Various elastomeric materials often are used in the manufacture ofvulcanizates such as, e.g., tire components. In addition to naturalrubber, some of the most commonly employed include high-cispolybutadiene, often made by processes employing catalysts, andsubstantially random styrene/butadiene interpolymers, often made byprocesses employing anionic initiators. Functionalities that can beincorporated into catalyzed polymers often cannot be incorporated intoanionically initiated polymers and vice versa.

Of particular difficulty to synthesize are interpolymers of olefins andpolyenes, particularly conjugated dienes, due in large part to theirvery different reactivities, i.e., susceptibility to coordinate withcatalytic metal atoms and thereby polymerize. Although difficult tosynthesize, such interpolymers have many commercial uses.

SUMMARY

Any of a class of lanthanide metal complexes can be used as aningredient of a catalyst system. The catalyst system can be used inpolymerizations of ethylenically unsaturated hydrocarbon monomers.

The class of lanthanide metal complexes can be represented by thegeneral formula

where M represents a lanthanide metal atom; L represents a neutral Lewisbase; z is an integer of from 0 to 2 inclusive; R¹ is a divalent atom orgroup that contains at least one of C, O, S, N, P, Si, Se, Sn or B; eachR² independently is H, a halogen atom, substituted or unsubstitutedhydrocarbyl group, the radical of a heterocyclic compound, or aheteroatom-containing group; and R³ is a halogen-containing group, agroup that contains an Al atom, or R². In the foregoing, two R² groupsor one R² group and R¹ or R³, together with the atoms to which each isbonded, can form a ring structure. Alternatively or additionally, R¹ andR³, together with the atoms to which each is bonded, can form a ringstructure. Methods of making this complex also are provided.

In other aspects are provided a catalyst composition that includes thelanthanide metal complex set forth above with a catalyst activator, aswell as methods of making the composition.

In a still further aspect is provided a process of polymerizingethylenically unsaturated hydrocarbon monomers. The method involvescontacting the monomers with the aforedescribed catalyst composition.The ethylenically unsaturated hydrocarbon monomers can include one ormore types of polyene and, optionally, one or more types of olefin.Where one or more types of olefin are present in the monomers, theresulting interpolymer typically contains at least 50 mole percentpolyene mer.

The foregoing process also can include providing the resulting polymerwith a terminal moiety so as to enhance the ability of the polymer tointeract with particulate filler such as, e.g., carbon black and/orsilica. Compositions, including vulcanizates, that include particulatefillers and such polymers also are provided, as are methods of providingand using such compositions.

Other aspects of the invention will be apparent to the ordinarilyskilled artisan from the detailed description that follows. To assist inunderstanding that description, certain definitions are providedimmediately below, and these are intended to apply throughout unless thesurrounding text explicitly indicates a contrary intention:

-   -   “polymer” means the polymerization product of one or more        monomers and is inclusive of homo-, co-, ter-, tetra-polymers,        etc.;    -   “mer” or “mer unit” means that portion of a polymer derived from        a single reactant molecule (e.g., ethylene mer has the general        formula —CH₂CH₂—);    -   “copolymer” means a polymer that includes mer units derived from        two reactants, typically monomers, and is inclusive of random,        block, segmented, graft, etc., copolymers;    -   “interpolymer” means a polymer that includes mer units derived        from at least two reactants, typically monomers, and is        inclusive of copolymers, terpolymers, tetra-polymers, and the        like;    -   “substituted” means containing a heteroatom or functionality        (e.g., hydrocarbyl group) that does not interfere with the        intended purpose of the group in question;    -   “heteroatom,” when used in the phrase “heteroatom-containing        group,” means O, S, N, B, P, Si, Ge or Sn;    -   “heterocyclic compound” means a cyclic compound that includes        within the ring structure a heteroatom;    -   “polyene” means a molecule, typically a monomer, with at least        two double bonds located in the longest portion or chain        thereof, and specifically is inclusive of dienes, trienes, and        the like;    -   “polydiene” means a polymer that includes mer units from one or        more dienes;    -   “phr” means parts by weight (pbw) per 100 pbw rubber;    -   “radical” means the portion of a molecule that remains after        reacting with another molecule, regardless of whether any atoms        are gained or lost as a result of the reaction;    -   “non-coordinating anion” means a sterically bulky anion that        does not form coordinate bonds with, for example, the active        center of a catalyst system due to steric hindrance;    -   “non-coordinating anion precursor” means a compound that is able        to form a non-coordinating anion under reaction conditions;    -   “ring system” means a single ring or two or more fused rings or        rings linked by a single bond, with the proviso that each ring        includes unsaturation;    -   “terminus” means an end of a polymeric chain;    -   “terminally active” means a polymer with a living or        pseudo-living terminus; and    -   “terminal moiety” means a group or functionality located at a        terminus.

Throughout this document, all values given in the form of percentagesare weight percentages unless the surrounding text explicitly indicatesa contrary intention. The relevant portion(s) of any specificallyreferenced patent and/or published patent application are incorporatedherein by reference.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

As apparent from the foregoing, the catalyst composition can be used topolymerize polyenes and, optionally, olefins. The resulting polymer canbe elastomeric, including mer units that include ethylenic unsaturation.Mer units that include ethylenic unsaturation can be derived frompolyenes, particularly dienes and trienes (e.g., myrcene). Illustrativepolyenes include C₄-C₃₀ dienes, preferably C₄-C₁₂ dienes. Preferredamong these are conjugated dienes such as, but not limited to,1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 1,3-octadiene,2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene,2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene,4-methyl-1,3-pentadiene, 2,4-hexadiene, and the like.

Polyenes can incorporate into polymeric chains in more than one way, andcontrolling this manner of incorporation can be desirable, particularlyfor tire tread applications. A polymer chain with an overall1,2-microstructure, given as a numerical percentage based on totalpolyene content, of from ˜10 to ˜80%, optionally from ˜25 to ˜65%, canbe desirable for certain end use applications. A polymer that has anoverall 1,2-microstructure of no more than ˜50%, preferably no more than˜45%, more preferably no more than ˜40%, even more preferably no morethan ˜35%, and most preferably no more than ˜30%, based on total polyenecontent, is “substantially linear.” For certain end use applications,however, keeping the content of 1,2-linkages even lower—e.g., to lessthan 20%, less than 15%, less than 10%, less than 7%, less than 5%, lessthan 2%, or less than 1%—can be desirable.

For those polyene mer not having 1,2-microstructure, i.e., those havinga 1,4-linkage, such mer can incorporate in either a cis or transconfiguration. The present process can provide polymers with polydienemer having a cis-1,4-linkage content of at least ˜60%, at least ˜75%, atleast ˜85%, at least ˜90%, and even at least ˜95%.

Examples of olefins that can be employed in the process include C₂-C₃₀straight chain or branched α-olefins such as ethylene, propylene,1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene,3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene,1-hexadecene, 1-octadecene, 1-eicosene, and the like, as well as C₃-C₃₀cycloolefins such as cyclopentene, cycloheptene, norbornene,5-methyl-2-norbornene, and tetracyclododecene. Smaller olefins such asethylene and propylene are preferred.

The polymerization process can provide an olefin/polyene interpolymerwith a predominant amount of polyene mer, e.g., an olefin/conjugateddiene copolymer that includes a predominant amount of conjugated dienemer. The resulting interpolymer can contain up to 10, 20 or even 30 molepercent olefin mer and at least 70, 80 or even 90 mole percent polyenemer. The interpolymer can include from 1 to 30 mole percent olefin merand from 70 to 99 mole percent conjugated diene mer, from 1 to 20 molepercent olefin mer and from 80 to 99 mole percent conjugated diene mer,or from 1 to 10 mole percent olefin mer and from 10 to 99 mole percentconjugated diene mer.

The number average molecular weight (M_(n)) of the polymer typically issuch that a quenched sample exhibits a gum Mooney viscosity (ML₄/100°C.) of from ˜2 to ˜150, more commonly from ˜2.5 to ˜125, even morecommonly from ˜5 to ˜100, and most commonly from ˜10 to ˜75; theforegoing generally corresponds to a molecular weight of from ˜5,000 to˜250,000 Daltons, commonly from ˜10,000 to ˜150,000 Daltons, morecommonly from ˜50,000 to ˜120,000 Daltons, and most commonly from˜10,000 to ˜100,000 Daltons or even 10,000 to 80,000 Daltons. Theresulting interpolymer typically has a molecular weight distribution(M_(w)/M_(n)) of from 1 to 5, commonly from 2 to 5, more commonly from˜2.0 to ˜4.0. (Both M_(n) and M_(w) can be determined by GPC calibratedwith polystyrene standards.)

The foregoing types of polymers can be made by solution polymerization,which affords exceptional control of properties as randomness,microstructure, etc. Solution polymerizations have been performed sinceabout the mid-20th century, so the general aspects thereof are known tothe ordinarily skilled artisan; nevertheless, certain aspects areprovided here for convenience of reference.

Suitable solvents include those organic compounds that do not undergopolymerization or incorporation into propagating polymer chains (i.e.,are inert toward and unaffected by the catalyst composition) andpreferably are liquid at ambient temperature and pressure. Examples ofsuitable organic solvents include hydrocarbons with a low or relativelylow boiling point such as aromatic hydrocarbons, aliphatic hydrocarbons,and cycloaliphatic hydrocarbons. Exemplary polymerization solventsinclude various C₅-C₁₂ cyclic and acyclic alkanes (e.g., n-pentane,n-hexane, n-heptane, n-octane, n-nonane, n-decane, isopentane,isohexanes, isopentanes, isooctanes, 2,2-dimethylbutane, cyclopentane,cyclohexane, methylcyclopentane, methylcyclohexane, etc.) as well astheir alkylated derivatives, certain liquid aromatic compounds (e.g.,benzene, toluene, xylenes, ethylbenzene, diethylbenzene, andmesitylene), petroleum ether, kerosene, petroleum spirits, and mixturesthereof. Other potentially suitable organic compounds that can be usedas solvents include high-boiling hydrocarbons of high molecular weightssuch as paraffinic oil, aromatic oil, or other hydrocarbon oils that arecommonly used to oil-extend polymers. The ordinarily skilled artisan isaware of other useful solvent options and combinations.

In solution polymerizations, vinyl content (i.e., 1,2-microstructure)can be adjusted through inclusion of a coordinator, usually a polarcompound, in the polymerization ingredients. Up to 90 or moreequivalents of coordinator can be used per equivalent of initiator, withthe amount depending on, e.g., the amount of vinyl content desired, thelevel of non-polyene monomer employed, the reaction temperature, andnature of the specific coordinator employed. Compounds useful ascoordinators include organic compounds that include a heteroatom havinga non-bonded pair of electrons (e.g., O or N). Examples include dialkylethers of mono- and oligo-alkylene glycols; crown ethers; tertiaryamines such as tetramethylethylene diamine; THF; THF oligomers; linearand cyclic oligomeric oxolanyl alkanes (see, e.g., U.S. Pat. No.4,429,091) such as 2,2-bis(2′-tetrahydrofuryl)propane, dipiperidylethane, hexamethylphosphoramide, N,N′-dimethylpiperazine,diazabicyclooctane, diethyl ether, tributylamine, and the like.

Although the ordinarily skilled artisan understands the conditionstypically employed in solution polymerization, a representativedescription is provided for convenience of the reader. The following isbased on a batch process, although extending this description to, e.g.,semi-batch or continuous processes is within the capability of theordinarily skilled artisan.

Certain end use applications call for polymers that have properties thatcan be difficult or inefficient to achieve via anionic (living)polymerizations. For example, in some applications, conjugated dienepolymers having high cis-1,4-linkage contents can be desirable, andthese commonly are prepared by processes using catalysts (as opposed tothe initiators employed in living polymerizations) and may displaypseudo-living characteristics.

The polymerization process employs a lanthanide catalyst composition.The term “catalyst composition” encompasses a simple mixture ofingredients, a complex of various ingredients that is caused by physicalor chemical forces of attraction, a chemical reaction product of some orall of the ingredients, or a combination of the foregoing.

Commonly employed lanthanide catalyst compositions include (a) alanthanide compound, an alkylating agent and optionally ahalogen-containing compound (where neither the lanthanide compound orthe alkylating agent contains a halogen atom); (b) a lanthanide compoundand an aluminoxane; or (c) a lanthanide compound, an alkylating agent,and a non-coordinating anion or precursor thereof.

The polymerization process described herein employs a specific group oflanthanide complexes, specifically, those defined by formula (I) setforth above. The following paragraphs refer to that group of complexes.

In formula (I), M represents a lanthanide metal atom, i.e., elementswith atomic numbers 57 to 71: La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy,Ho, Er, Tm, Yb, and Lu. Preferred lanthanide metals are Nd and Gd. M canbe in any of a number of oxidation states, with +2 to +5 being mostcommon and +3 being perhaps the most common.

L represents a neutral Lewis base, examples of which include but notlimited to (thio)ethers, cyclic (thio)ethers, amines, cyclic amines,phosphines, and cyclic phosphines. Specific non-limiting examples of Lgroups include THF, diethyl ether, dimethyl aniline, trimethylphosphine, neutral olefins, neutral diolefins, and the like.

Because z can be an integer of from 0 to 2 (determined by the availablecoordination number(s) of M), the complex can contain a plurality of Lgroups. In the case where z is 2, each L can be the same or different.

R¹ is a divalent group that contains at least one of C, O, S, N, P, Si,Se, Sn or B. Those of the foregoing elements which are (or can be)divalent, e.g., O, S and Se, can act as a divalent “group,” while theother elements can constitute part of a multi-atom group, preferably onewith 2-40, more preferably with 2-10, atoms in the longest chainthereof. Specific non-limiting examples of multi-atom R¹ divalent groupsinclude NH, PH, BH, BF, SiH₂, SnH₂ and NR, PR, BR, SiR₂ or SnR₂ where Ris a hydrocarbyl group, preferably a C₁-C₃ alkyl group.

Each R² independently is H, a halogen atom (i.e., F, Cl, Br or I), asubstituted or unsubstituted hydrocarbyl group, the radical of aheterocyclic compound, or a heteroatom-containing group; if an R² is ahalogen, it preferably is Cl or Br. In some embodiments, two or more R²groups together with the C atoms to which each is bonded can form a ringstructure. In other embodiments, one or more R² groups and R¹, togetherwith the atoms to which each is bonded, can form a ring structure. Theresulting ring structure(s) can be aliphatic, aromatic or heterocyclicand optionally can contain one or more substituents.

R³ is a halogen-containing group such as PF₅, BF₃, ClO₄, SbCl₆, IO₄, andthe like; a group that contains an Al atom; or R². If an R³ is ahalogen, it preferably is Cl or Br, with Cl being particularly preferredas R³. Alternatively, R³ with an R² group (or less frequently an R¹group), together with the atoms to which each is bonded, can form aring.

Exemplary hydrocarbyl groups include straight-chain or branched C₁-C₃₀alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, sec-butyl, tert-butyl, neopentyl, n-hexyl, octyl and the like;straight-chain or branched C₂-C₃₀ alkenyl groups such as vinyl, allyl,and isopropenyl; straight-chain or branched C₂-C₃₀ alkynyl groups suchas ethynyl and propargyl; C₂-C₃₀ saturated cyclic groups such ascyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and adamantyl; C₅-C₃₀unsaturated cyclic groups such as cyclopentadienyl, indenyl, andfluorenyl; and C₆-C₃₀ aryl groups such as phenyl, tolyl, benzyl,naphthyl, biphenyl, phenanthryl, antracenyl and terphenyl.

The hydrocarbyl groups can be substituted with halogen atoms (e.g.,halogenated C₁-C₃₀ hydrocarbyl groups such as trifluoromethyl,pentafluorophenyl, and chlorophenyl), other hydrocarbyl groups (e.g.,aryl-substituted alkyl groups such as benzyl and cumyl),heteroatom-containing groups (e.g., alkoxy, aryloxy such as2,6-dimethylphenoxy or 2,4,6-trimethylphenoxy, acyl such asp-chlorobenzoyl or p-methoxybenzoyl, (thio)carboxyl, carbonato, hydroxy,peroxy, (thio)ester such as acetyloxy or benzoyloxy, (thio)ether,anhydride, amino, imino, amide such as acetamido or N-methylacetamido,imide such as acetimido and benzimido, hydrazino, hydrazono, nitro,nitroso, cyano, isocyano, (thio)cyanic acid ester, amidino, diazo,borandiyl, borantriyl, diboranyl, mercapto, dithioester, alkylthio,arylthio such as (methyl)phenylthio, or naphthylthio, thioacyl,isothiocyanic acid ester, sulfonester, sulfonamide, dithiocarboxyl,sulfo, sulfonyl, sulfinyl, sulfenyl, phosphido, (thio)-phosphoryl,phosphato, silyl, siloxy, hydrocarbyl-substituted silyl groups such asmethylsilyl, dimethylsilyl, trimethylsilyl, ethylsilyl, diethylsilyl,triethylsilyl, diphenylmethylsilyl, triphenylsilyl, dimethylphenylsilyl,dimethyl-t-butylsilyl, dimethyl(pentafluorophenyl)silyl,bistrimethylsilylmethyl, and hydrocarbyl-substituted siloxy groups suchas trimethylsiloxy), and the like. (Replacing the silicon atom in theSi-containing groups with Ge or Sn can provide useful Ge- orSn-containing groups.) The Al- and B-containing groups can berepresented, respectively, by AlR⁵ ₄ and BR⁵ _(m) where m is 2 or 3 andR⁵ is H, a halogen atom, a substituted or unsubstituted aryl group, etc.

Preferred hydrocarbyl groups include straight-chain or branched C₁-C₃₀alkyl groups, C₆-C₃₀ aryl groups, and aryl groups substituted with 1 to5 substituents, such as C₁-C₃₀ alkyl or alkoxy groups and C₆-C₃₀ aryl oraryloxy groups.

Exemplary heterocyclic compounds include N-containing heterocycles suchas pyrrole, pyridine, pyrimidine, quinoline, and triazine, O-containingheterocycles such as furan and pyran, and S-containing heterocycles suchas thiophene. The heterocyclic compounds can include substituents suchas, but not limited to, C₁-C₂₀ alkyl or alkoxy groups.

Formula I-type compounds can be prepared following the proceduresdescribed in, for example, U.S. Pat. No. 7,300,903 (and substituting alanthanide series metal compound for the transition metal compounds usedthere). The examples section below contains specific exemplaryprocedures.

Component (b) of the lanthanide catalyst composition, referred to hereinas a co-catalyst or catalyst activator, includes an alkylating agentand/or a compound containing a non-coordinating anion or anon-coordinating anion precursor.

An alkylating agent can be considered to be an organometallic compoundthat can transfer hydrocarbyl groups to another metal. Typically, theseagents are organometallic compounds of electropositive metals such asGroups 1, 2, and 3 metals. Exemplary alkylating agents includeorganoaluminum compounds such as those having the general formula AlR⁶_(n)X_(3-n) (where n is an integer of from 1 to 3 inclusive; each R⁶independently is a monovalent organic group, which may containheteroatoms such as N, O, B, Si, S, P, and the like, connected to the Alatom via a C atom; and each X independently is H, a halogen atom, acarboxylate group, an alkoxide group, or an aryloxide group). In one ormore embodiments, each R⁶ independently can be a hydrocarbyl group suchas, for example, alkyl, cycloalkyl, substituted cycloalkyl, alkenyl,cycloalkenyl, substituted cycloalkenyl, aryl, substituted aryl, aralkyl,alkaryl, allyl, and alkynyl groups, with each group containing from 1 Catom, or the appropriate minimum number of C atoms to form the group, upto ˜20 C atoms. These hydrocarbyl groups may contain heteroatomsincluding, but not limited to, N, O, B, Si, S, and P atoms. Non-limitingspecies of organoaluminum compounds within this general formula include

-   -   trihydrocarbylaluminum compounds such as trimethylaluminum,        triethylaluminum, triisobutylaluminum, tri-n-propylaluminum,        triisopropylaluminum, tri-n-butylaluminum, tri-t-butylaluminum,        tri-n-pentylaluminum, trineopentylaluminum, tri-n-hexylaluminum,        tri-n-octylaluminum, tris(2-ethylhexyl)aluminum,        tricyclohexylaluminum, tris(1-methylcyclopentyl)aluminum,        triphenylaluminum, tri-p-tolylaluminum,        tris(2,6-dimethylphenyl)aluminum, tribenzylaluminum,        diethylphenylaluminum, diethyl-p-tolylaluminum,        diethylbenzylaluminum, ethyldiphenylaluminum,        ethyldi-p-tolylaluminum, and ethyldi-benzylaluminum;    -   dihydrocarbylaluminum hydrides such as diethylaluminum hydride,        di-n-propylaluminum hydride, diisopropylaluminum hydride,        di-n-butylaluminum hydride, diisobutylaluminum hydride,        di-n-octylaluminum hydride, diphenylaluminum hydride,        di-p-tolylaluminum hydride, dibenzylaluminum hydride,        phenylethylaluminum hydride, phenyl-n-propylaluminum hydride,        phenylisopropylaluminum hydride, phenyl-n-butylaluminum hydride,        phenylisobutylaluminum hydride, phenyl-n-octylaluminum hydride,        p-tolylethylaluminum hydride, p-tolyl-n-propylaluminum hydride,        p-tolylisopropylaluminum hydride, p-tolyl-nbutylaluminum        hydride, p-tolylisobutylaluminum hydride,        p-tolyl-n-octylaluminum hydride, benzylethylaluminum hydride,        benzyl-n-propylaluminum hydride, benzylisopropylaluminum        hydride, benzyl-n-butylaluminum hydride, benzylisobutylaluminum        hydride, and benzyl-n-octylaluminum hydride;    -   hydrocarbylaluminum dihydrides such as ethylaluminum dihydride,        n-propylaluminum dihydride, isopropylaluminum dihydride,        nbutylaluminum dihydride, isobutylaluminum dihydride, and        n-octylaluminum dihydride;    -   dihydrocarbylaluminum carboxylates;    -   hydrocarbylaluminum bis(carboxylate)s;    -   dihydrocarbylaluminum alkoxides;    -   hydrocarbylaluminum dialkoxides;    -   dihydrocarbylaluminum halides such as diethylaluminum chloride,        di-n-propylaluminum chloride, diisopropylaluminum chloride,        di-n-butylaluminum chloride, diisobutylaluminum chloride,        di-n-octylaluminum chloride, diphenylaluminum chloride,        di-p-tolylaluminum chloride, dibenzylaluminum chloride,        phenylethylaluminum chloride, phenyl-n-propylaluminum chloride,        phenylisopropylaluminum chloride, phenyl-n-butylaluminum        chloride, phenylisobutylaluminum chloride,        phenyl-n-octylaluminum chloride, ptolylethylaluminum chloride,        p-tolyl-n-propylaluminum chloride, p-tolylisopropylaluminum        chloride, p-tolyl-n-butylaluminum chloride,        p-tolylisobutylaluminum chloride, p-tolyl-noctylaluminum        chloride, benzylethylaluminum chloride, benzyl-n-propylaluminum        chloride, benzylisopropylaluminum chloride,        benzyl-n-butylaluminum chloride, benzylisobutylaluminum        chloride, and benzyl-n-octylaluminum chloride;    -   hydrocarbylaluminum dihalides such as ethylaluminum dichloride,        n-propylaluminum dichloride, isopropylaluminum dichloride,        n-butylaluminum dichloride, isobutylaluminum dichloride, and        n-octylaluminum dichloride;    -   dihydrocarbylaluminum aryloxides; and    -   hydrocarbylaluminum diaryloxides.        In certain embodiments, the alkylating agent can include        trihydrocarbylaluminum, dihydrocarbylaluminum hydride, and/or        hydrocarbylaluminum dihydride.

Other organoaluminum compounds that can serve as alkylating agentsinclude, but are not limited to, dimethylaluminum hexanoate,diethylaluminum octoate, diisobutylaluminum 2-ethylhexanoate,dimethylaluminum neodecanoate, diethylaluminum stearate,diisobutylaluminum oleate, methylaluminum bis(hexanoate), ethylaluminumbis(octoate), isobutylaluminum bis(2-ethylhexanoate), methylaluminumbis(neodecanoate), ethylaluminum bis(stearate), isobutylaluminumbis(oleate), dimethylaluminum methoxide, diethylaluminum methoxide,diisobutylaluminum methoxide, dimethylaluminum ethoxide, diethylaluminumethoxide, diisobutylaluminum ethoxide, dimethylaluminum phenoxide,diethylaluminum phenoxide, diisobutylaluminum phenoxide, methylaluminumdimethoxide, ethylaluminum dimethoxide, isobutylaluminum dimethoxide,methylaluminum diethoxide, ethylaluminum diethoxide, isobutylaluminumdiethoxide, methylaluminum diphenoxide, ethylaluminum diphenoxide, andisobutylaluminum diphenoxide.

Another class of organoaluminum compounds suitable for use as analkylating agent is aluminoxanes. This class includes oligomeric linearaluminoxanes and oligomeric cyclic aluminoxanes, formulas for both beingprovided in a variety of references including, for example, U.S. Pat.No. 8,017,695. (Where the oligomeric type of compound is used as analkylating agent, the number of moles refers to the number of moles ofAl atoms rather than the number of moles of oligomeric molecules, aconvention commonly employed in the art of catalyst systems utilizingaluminoxanes.)

Aluminoxanes can be prepared by reacting trihydrocarbylaluminumcompounds with water. This reaction can be performed according to knownmethods such as, for example, (1) dissolving the trihydrocarbylaluminumcompound in an organic solvent and then contacting it with water, (2)reacting the trihydrocarbylaluminum compound with water ofcrystallization contained in, for example, metal salts, or wateradsorbed in inorganic or organic compounds, or (3) reacting thetrihydrocarbylaluminum compound with water in the presence of themonomer(s) to be polymerized.

Suitable aluminoxane compounds include, but are not limited to,methylaluminoxane (“MAO”), modified methylaluminoxane (“MMAO,” formed bysubstituting ˜20 to 80% of the methyl groups of MAO with C₂-C₁₂hydrocarbyl groups, preferably with isobutyl groups, using knowntechniques), ethylaluminoxane, n-propylaluminoxane,isopropylaluminoxane, butylaluminoxane, isobutylaluminoxane,n-pentylaluminoxane, neopentylaluminoxane, n-hexylaluminoxane,n-octylaluminoxane, 2-ethylhexylaluminoxane, cyclohexylaluminoxane,1-methylcyclopentylaluminoxane, phenylaluminoxane, and2,6-dimethylphenylaluminoxane.

Aluminoxanes can be used alone or in combination with otherorganoaluminum compounds. In one embodiment, MAO and at least one otherorganoaluminum compound such as diisobutyl aluminum hydride can beemployed in combination. The interested reader is directed to U.S.Patent Publ. No. 2008/0182954 for other examples of aluminoxanes andorganoaluminum compounds employed in combination.

Also suitable as alkylating agents are organomagnesium compounds such asthose having the general formula R⁷ _(m)MgX_(2-m) where X is defined asabove, m is 1 or 2, and R⁷ is the same as R⁶ except that each monovalentorganic group is connected to the Mg atom via a C atom. Potentiallyuseful organomagnesium compounds include, but are not limited to,diethylmagnesium, di-n-propylmagnesium, diisopropylmagnesium,dibutylmagnesium, dihexylmagnesium, diphenylmagnesium,dibenzylmagnesium, hydrocarbylmagnesium hydride (e.g., methylmagnesiumhydride, ethylmagnesium hydride, butylmagnesium hydride, hexylmagnesiumhydride, phenylmagnesium hydride, benzylmagnesium hydride),hydrocarbylmagnesium halide (e.g., methylmagnesium chloride,ethylmagnesium chloride, butylmagnesium chloride, hexylmagnesiumchloride, phenylmagnesium chloride, benzylmagnesium chloride,methylmagnesium bromide, ethylmagnesium bromide, butylmagnesium bromide,hexylmagnesium bromide, phenylmagnesium bromide, benzylmagnesiumbromide), hydrocarbylmagnesium carboxylate (e.g., methylmagnesiumhexanoate, ethylmagnesium hexanoate, butylmagnesium hexanoate,hexylmagnesium hexanoate, phenylmagnesium hexanoate, benzylmagnesiumhexanoate), hydrocarbylmagnesium alkoxide (e.g. methylmagnesiumethoxide, ethylmagnesium ethoxide, butylmagnesium ethoxide,hexylmagnesium ethoxide, phenylmagnesium ethoxide, benzylmagnesiumethoxide), and hydrocarbylmagnesium aryloxide (e.g., methylmagnesiumphenoxide, ethylmagnesium phenoxide, butylmagnesium phenoxide,hexylmagnesium phenoxide, phenylmagnesium phenoxide, and benzylmagnesiumphenoxide).

The catalyst composition also or alternatively can contain anon-coordinating anion or a non-coordinating anion precursor. Exemplarynon-coordinating anions include tetravalent B anions such astetraarylborate anions, particularly fluorinated tetraarylborate anions.Specific examples of non-coordinating anions include tetraphenylborate,tetrakis-(monofluorophenyl)borate, tetrakis(difluorophenyl)borate,tetrakis(trifluororphenyl)borate, tetrakis(tetrafluorophenyl)borate,tetrakis(pentafluorophenyl)borate,tetrakis(tetrafluoromethylphenyl)borate, tetra(tolyl)borate,tetra(xylyl)borate, (triphenyl, pentafluorophenyl)borate,[tris(pentafluorophenyl), phenyl]borate,tridecahydride-7,8-dicarbaundecaborate and the like.Tetrakis(pentafluorophenyl)borate is among the preferrednon-coordinating anions.

Compounds containing a non-coordinating anion also contain acountercation such as a carbonium (e.g., tri-substituted carboniumcation such as triphenylcarbonium cation, tri(substitutedphenyl)carbonium cation (e.g., tri(methylphenyl)carbonium cation),oxonium, ammonium (e.g., trialkyl ammonium cations, N,N-dialkylanilinium cations, dialkyl ammonium cations, etc.), phosphonium (e.g.,triaryl phosphonium cations such as triphenyl phosphonium cation,tri(methylphenyl)phosphonium cation, tri(dimethylphenyl)-phosphoniumcation, etc.), cycloheptatrieneyl, or ferrocenium cation (or similar).Among these, N,N-dialkyl anilinium or carbonium cations are preferred,with the former being particularly preferred.

Examples of compounds containing a non-coordinating anion and a countercation include triphenylcarbonium tetrakis(pentafluorophenyl)borate,N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate,triphenylcarbonium tetrakis[3,5-bis(trifluoromethyl)-phenyl]borate, andN,N-dimethylanilinium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate.

Exemplary non-coordinating anion precursors include boron compounds thatinclude strong electron-withdrawing groups. Specific examples includetriarylboron compounds where each aryl group is strongly electronwithdrawing, e.g., pentafluorophenyl or 3,5-bis(trifluoromethyl)phenyl.

Catalyst compositions of the type just described have very highcatalytic activity for polymerizing polyenes such as conjugated dienes(and optionally olefins, particularly α-olefins) into stereospecificpolymers over a wide range of concentrations and ratios, althoughpolymers having the most desirable properties typically are obtainedfrom systems that employ a relatively narrow range of concentrations andratios of ingredients. Further, the catalyst ingredients are believed tointeract to form an active catalyst species, so the optimumconcentration for each ingredient can depend on the concentrations ofthe other ingredients. The following molar ratios are considered to berelatively exemplary for a variety of different systems based on theforegoing ingredients:

-   -   alkylating agent to lanthanide complex (alkylating agent/Ln):        from ˜1:1 to ˜1000:1, commonly from ˜2:1 to ˜500:1, typically        from ˜5:1 to ˜200:1;    -   aluminoxane to lanthanide complex, specifically equivalents of        aluminum atoms in the aluminoxane to equivalents of lanthanide        atoms in the lanthanide complex (Al/Ln): from ˜5:1 to ˜1000:1,        commonly from ˜10:1 to ˜700:1, typically from ˜20:1 to ˜500:1;    -   organoaluminum compound to lanthanide complex (oAl/Ln): from        ˜1:1 to ˜200:1, commonly from ˜2:1 to ˜150:1, typically from        ˜5:1 to ˜100:1; and    -   non-coordinating anion or precursor to lanthanide complex        (An/Ln): from ˜1:2 to ˜20:1, commonly from ˜3:4 to ˜10:1,        typically from ˜1:1 to ˜6:1.

The molecular weight of polymers produced with a lanthanide-basedcatalyst composition can be controlled by adjusting the amount ofcatalyst used and/or the amounts of co-catalyst concentrations withinthe catalyst system; polymers having a wide range of molecular weightscan be produced in this manner. In general, increasing the catalyst andco-catalyst concentrations reduces the molecular weight of resultingpolymers, although very low molecular weight polymers (e.g., liquidpolydienes) require extremely high catalyst concentrations. Typically,this necessitates removal of catalyst residues from the polymer to avoidadverse effects such as retardation of the sulfur cure rate.

A lanthanide-based catalyst composition can be formed using any of thefollowing methods:

-   -   (1) In situ. The catalyst ingredients are added to a solution        containing monomer and solvent (or simply bulk monomer). The        addition can occur in a stepwise or simultaneous manner. In the        case of the latter, the alkylating agent preferably is added        first followed by the lanthanide complex.    -   (2) Pre-mixed. The ingredients can be mixed outside the        polymerization system, generally at a temperature of from about        −20° to ˜80° C., before being introduced to the monomer(s).    -   (3) Pre-formed in the presence of monomer(s). The catalyst        ingredients are mixed in the presence of a small amount of        monomer(s) at a temperature of from about −20° to ˜80° C. The        amount of conjugated diene monomer can range from ˜1 to ˜500        moles, commonly from ˜5 to ˜250 moles, typically from ˜10 to        ˜100 moles, per mole of the lanthanide complex. The resulting        catalyst composition is added to the remainder of the monomer(s)        to be polymerized.    -   (4) Two-stage procedure.        -   (a) The alkylating agent is combined with the lanthanide            complex in the absence of monomer or in the presence of a            small amount of monomer(s) at a temperature of from about            −20° to ˜80° C.        -   (b) The foregoing mixture and the remaining components are            charged in either a stepwise or simultaneous manner to the            remainder of the monomer(s) to be polymerized.            When a solution of one or more of the catalyst ingredients            is prepared outside the polymerization system in the            foregoing methods, an organic solvent or carrier is            preferably employed; useful organic solvents include those            mentioned previously. In other embodiments, one or more            monomers can be used as a carrier or the catalyst            ingredients can be employed neat, i.e., free of any solvent            of other carrier.

In one or more embodiments, some or all of the catalyst composition canbe supported on an inert carrier. The support can be a porous solid suchas talc, a sheet silicate, an inorganic oxide or a finely dividedpolymer powder. Suitable inorganic oxides are oxides of elements fromany of Groups 2-5 and 13-16. Examples of preferred supports includeSiO₂, aluminum oxide, and also mixed oxides of the elements Ca, Al, Si,Mg or Ti and also corresponding oxide mixtures, Mg halides,styrene/divinylbenzene copolymers, polyethylene or polypropylene.

The production of polymers such as cis-1,4-polydiene (or interpolymersthat include cis-1,4-diene mer) is accomplished by polymerizingconjugated diene monomer(s) in the presence of a catalytically effectiveamount of a catalyst composition. The total catalyst concentration to beemployed in the polymerization mass depends on the interplay of variousfactors such as the purity of the ingredients, the polymerizationtemperature, the polymerization rate and conversion desired, themolecular weight desired, and many other factors; accordingly, aspecific total catalyst concentration cannot be definitively set forthexcept to say that catalytically effective amounts of the respectivecatalyst ingredients should be used. The amount of the lanthanidecomplex used generally ranges from ˜0.01 to ˜2 mmol, commonly from ˜0.02to ˜1 mmol, typically from ˜0.05 to ˜0.5 mmol per 100 g monomer. Allother ingredients generally can be added in amounts based on the amountof lanthanide complex; see the various ratios set forth above.

Where an olefin interpolymer is desired, the molar ratio of polyene(e.g., conjugated diene) to olefin introduced into the reaction vesselcan vary over a wide range. For example, the molar ratio of polyene(e.g., conjugated diene) to olefin can range from ˜100:1 to 1:100,commonly from ˜20:1 to 1:20, and typically from ˜5:1 to 1:5.

Polymerization preferably is carried out in one or more organic solventsof the type(s) set forth above, i.e., as a solution polymerization(where both the monomer(s) and the polymers formed are soluble in thesolvent) or precipitation polymerization (where the monomer is in acondensed phase but the polymer products are insoluble). The catalystingredients preferably are solubilized or suspended in the organicliquid, and additional solvent (beyond that used in preparing thecatalyst composition) usually is added to the polymerization system; theadditional solvent(s) may be the same as or different from thesolvent(s) used in preparing the catalyst system. In one or moreembodiments, the solvent content of the polymerization mixture may bemore than 20%, more than 50%, or even more than 80% (by wt.) of thetotal weight of the polymerization mixture. The concentration of monomerpresent at the beginning of the polymerization generally ranges from ˜3to ˜80%, commonly from ˜5 to ˜50%, and typically from ˜10% to ˜30% (bywt.).

In certain embodiments, a bulk polymerization system that includes nomore than a minimal amount of solvent can be used, i.e., a bulkpolymerization process where one or more of the monomers act(s) as thesolvent; examples of potentially useful bulk polymerization processesare disclosed in U.S. Patent Appl. Pub. No. 2005/0197474 A1. In a bulkpolymerization, the solvent content of the polymerization mixture may beless than ˜20%, less than ˜10%, or even less than ˜5% (by wt.) of thetotal weight of the polymerization mixture. The polymerization mixtureeven can be substantially devoid of solvent, i.e., contain less thanthat amount of solvent which otherwise would have an appreciable impacton the polymerization process.

The polymerization can be conducted in any of a variety of reactionvessels. For example, solution polymerizations can be conducted in aconventional stirred-tank reactor. Bulk polymerizations also can beconducted in a stirred-tank reaction if the monomer conversion is lessthan ˜60%. Where monomer conversion is higher than ˜60%, which typicallyresults in a highly viscous polymer cement (i.e., reaction mixture),bulk polymerization can be conducted in an elongated reactor in whichthe viscous cement is driven by, for example, piston or self-cleaningsingle- or double-screw agitator.

All components used in or during the polymerization can be combined in asingle vessel (e.g., a stirred-tank reactor), and the entirety of thepolymerization process can be conducted in that vessel. Alternatively,two or more of the ingredients can be combined outside thepolymerization vessel and transferred to another vessel wherepolymerization of the monomer(s), or at least a major portion thereof,can be conducted.

The polymerization can be carried out as a batch, continuous, orsemi-continuous process. The conditions under which the polymerizationproceeds can be controlled to maintain the temperature of thepolymerization mixture in a range of from −10° to ˜200° C., commonlyfrom ˜0° to ˜150° C., and typically from ˜20° to ˜100° C. Heat generatedby the polymerization can be removed by external cooling by a thermallycontrolled reactor jacket and/or internal cooling (by evaporation andcondensation of the monomer through use of a reflux condenser connectedto the reactor). Also, conditions may be controlled to conduct thepolymerization under a pressure of from ˜0.01 to ˜5 MPa, commonly from˜0.05 to ˜2 MPa, typically from ˜0.1 to ˜1 MPa; the pressure at whichthe polymerization is carried out can be such that the majority ofmonomers are in the liquid phase. In these or other embodiments, thepolymerization mixture may be maintained under anaerobic conditions,typically provided by an inert protective gas such as N₂, Ar or He.

Regardless of whether a batch, continuous, or semi-continuous process isemployed, the polymerization preferably is conducted with moderate tovigorous agitation.

The described polymerization process advantageously results in polymerchains that possess reactive (pseudo-living) terminals, which can befurther reacted with one or more functionalizing agents so as to providea polymer with a terminal functionality. These types polymers can bereferred to as functionalized and are distinct from a propagating chainthat has not been similarly reacted. In one or more embodiments,reaction between the functionalizing agent and the reactive polymer canproceed via an addition or substitution reaction.

The terminal functionality can be reactive or interactive with otherpolymer chains (propagating and/or non-propagating) or with othermaterials in a rubber compound such as particulate reinforcing fillers(e.g. carbon black). As described above, enhanced interactivity betweena polymer and particulate fillers in rubber compounds improves themechanical and dynamic properties of resulting vulcanizates. Forexample, certain functionalizing agents can impart a terminalfunctionality that includes a heteroatom to the polymer chain; suchfunctionalized polymer can be used in rubber compounds from whichvulcanizates can be provided, and that vulcanizates can possess hightemperature (e.g., 50° C.) hysteresis losses that are less than thosepossessed by vulcanizates prepared from similar rubber compounds that donot include such functionalized polymers. Reductions in high temperaturehysteresis loss can be at least 5%, sometimes at least 10%, andoccasionally at least 15%.

The functionalizing agent(s) can be introduced after a desired monomerconversion is achieved but prior to introduction of a quenching agent (acompound with a protic H atom) or after the polymerization mixture hasbeen partially quenched. The functionalizing agent can be added to thepolymerization mixture after a monomer conversion of at least 5%, atleast 10%, at least 20%, at least 50%, or at least 80%; in these orother embodiments, the functionalizing agent can be added to thepolymerization mixture prior to a monomer conversion of 90%, prior to70%, prior to 50%, prior to 20%, or prior to 15%. In certainembodiments, the functionalizing agent is added after complete, orsubstantially complete, monomer conversion. In particular embodiments, afunctionalizing agent may be introduced to the polymerization mixtureimmediately prior to, together with, or after the introduction of aLewis base as disclosed in U.S. Patent Publ. No. 2009/0043046 Al.

Useful functionalizing agents include compounds that simply provide afunctional group at the end of a polymer chain without joining two ormore polymer chains together, as well as compounds that can couple orjoin two or more polymer chains together via a functional linkage toform a single macromolecule. The ordinarily skilled artisan is familiarwith numerous examples of terminal functionalities that can be providedthrough this type of post-polymerization functionalization withterminating reagents, coupling agents and/or linking agents. Foradditional details, the interested reader is directed to any of U.S.Pat. Nos. 4,015,061, 4,616,069, 4,906,706, 4,935,471, 4,990,573,5,064,910, 5,153,159, 5,149,457, 5,196,138, 5,329,005, 5,496,940,5,502,131, 5,567,815, 5,610,227, 5,663,398, 5,567,784, 5,786,441,5,844,050, 6,812,295, 6,838,526, 6,992,147, 7,153,919, 7,294,680,7,642,322, 7,671,136, 7,671,138, 7,732,534, 7,750,087, 7,816,483,7,879,952, 8,063,153, 8,088,868, etc., as well as references cited inthese patents and later publications citing these patents; see also U.S.Patent Publ. Nos. 2007/0078232, 2008/0027171, and the like. Specificexemplary functionalizing compounds include metal halides (e.g., SnCl₄),R⁸ ₃SnCl, R⁸ ₂SnCl₂, R⁸SnCl₃, metalloid halides (e.g., SiCl₄),carbodiimides, ketones, aldehydes, esters, quinones, N-cyclic amides,N,N′-disubstituted cyclic ureas, cyclic amides, cyclic ureas, Schiffbases, iso(thio)cyanates, metal ester-carboxylate complexes (e.g.,dioxtyltin bis(octylmaleate), 4,4′-bis(diethylamino)benzophenone, alkylthiothiazolines, alkoxysilanes (e.g., Si(OR⁸)₄, R⁸Si(OR⁸)₃, R⁸₂Si(OR⁸)₂, etc.), cyclic siloxanes, alkoxystannates, and mixturesthereof. (In the foregoing, each R⁸ independently is a C₁-C₂₀ alkylgroup, C₃-C₂₀ cycloalkyl group, C₆-C₂₀ aryl group, or C₇-C₂₀ aralkylgroup.) Specific examples of preferred functionalizing compounds includeSnCl₄, tributyl tin chloride, dibutyl tin dichloride, and1,3-dimethyl-2-imidazolidinone (DMI).

The amount of functionalizing agent added to the polymerization mixturecan depend on various factors including the amount of catalyst used, thetype of functionalizing agent, the desired level of functionality, etc.In one or more embodiments, the amount of functionalizing agent may bein a range of from 1 to ˜200 moles, commonly from ˜5 to ˜150 moles, andtypically from ˜10 to ˜100 moles per mole of lanthanide complex.

Because reactive polymer chains can slowly self-terminate at hightemperatures, the functionalizing agent can be added to thepolymerization mixture once a peak polymerization temperature isobserved or, at least in some embodiments, within ˜25 to ˜35 minutesthereafter. Reaction of these types of compounds with a terminallyactive polymer can be performed relatively quickly (a few minutes to afew hours) at moderate temperatures (e.g., 0° to 75° C.).

The functionalizing agent can be introduced to the polymerizationmixture at a location (e.g., within a vessel) where the polymerization,or at least a portion thereof, has been conducted or at a locationdistinct therefrom. For example, the functionalizing agent can beintroduced to the polymerization mixture in downstream vessels includingdownstream reactors or tanks, in-line reactors or mixers, extruders, ordevolatilizers.

Although not mandatory, if desired, quenching can be performed toinactivate any residual reactive copolymer chains and the catalystcomposition. Quenching can be conducted by stirring the polymer and anactive hydrogen-containing compound, such as an alcohol or acid, for upto ˜120 minutes at temperatures of from ˜25° to ˜150° C. In someembodiments, the quenching agent can include a polyhydroxy compound asdisclosed in U.S. Pat. No. 7,879,958. An antioxidant such as2,6-di-t-butyl-4-methylphenol (BHT) may be added along with, before, orafter the addition of the quenching agent; the amount of antioxidantemployed can be from ˜0.2 to 1% (by wt.) of the polymer product. Thequenching agent and the antioxidant can be added neat or, if necessary,dissolved in a hydrocarbon solvent or liquid monomer prior to beingadded to the polymerization mixture.

Once polymerization, functionalization (if any) and quenching (if any)are complete, the various constituents of the polymerization mixture canbe recovered. Unreacted monomers can be recovered from thepolymerization mixture by, for example, distillation or use of adevolatilizer. Recovered monomers can be purified, stored, and/orrecycled back to the polymerization process.

The polymer product can be recovered from the polymerization mixtureusing known techniques. For example, the polymerization mixture can bepassed through a heated screw apparatus, such as a desolventizingextruder, in which volatile substances (e.g., low boiling solvents andunreacted monomers) are removed by evaporation at appropriatetemperatures (e.g., ˜100° to ˜170° C.) and under atmospheric orsub-atmospheric pressure. Another option involves steam desolvationfollowed by drying the resulting polymer crumbs in a hot air tunnel. Yetanother option involves recovering the polymer directly by drying thepolymerization mixture on a drum dryer. Any of the foregoing can becombined with coagulation with water, alcohol or steam; if coagulationis performed, oven drying may be desirable.

Recovered polymer can be grafted with other monomers and/or blended withother polymers (e.g., polyolefins) and additives to form resincompositions useful for various applications. The polymer, regardless ofwhether further reacted, is particularly suitable for use in themanufacture of various tire components including, but not limited to,tire treads, sidewalls, subtreads, and bead fillers. It also can be usedas a compatibilizer for elastomeric blends and/or used in themanufacture of hoses, belts, shoe soles, window seals, other seals,vibration damping rubber, and other industrial or consumer products.

When the resulting polymer is utilized in a tread stock compound, it canbe used alone or blended with any conventionally employed tread stockrubber including natural rubber and/or non-functionalized syntheticrubbers such as, e.g., one or more of homo- and interpolymers thatinclude just polyene-derived mer units (e.g., poly(butadiene),poly(isoprene), and copolymers incorporating butadiene, isoprene, andthe like), SBR, butyl rubber, neoprene, EPR, EPDM,acrylonitrile/butadiene rubber (NBR), silicone rubber, fluoroelastomers,ethylene/acrylic rubber, EVA, epichlorohydrin rubbers, chlorinatedpolyethylene rubbers, chlorosulfonated polyethylene rubbers,hydrogenated nitrile rubber, tetrafluoroethylene/propylene rubber andthe like. When a functionalized polymer(s) is blended with conventionalrubber(s), the amounts can vary from ˜5 to ˜99% of the total rubber,with the conventional rubber(s) making up the balance of the totalrubber. The minimum amount depends to a significant extent on the degreeof hysteresis reduction desired.

Amorphous silica (SiO₂) can be utilized as a filler. Silicas aregenerally classified as wet-process, hydrated silicas because they areproduced by a chemical reaction in water, from which they areprecipitated as ultrafine, spherical particles. These primary particlesstrongly associate into aggregates, which in turn combine less stronglyinto agglomerates. “Highly dispersible silica” is any silica having avery substantial ability to de-agglomerate and to disperse in anelastomeric matrix, which can be observed by thin section microscopy.

Surface area gives a reliable measure of the reinforcing character ofdifferent silicas; the Brunauer, Emmet and Teller (“BET”) method(described in J. Am. Chem. Soc., vol. 60, p. 309 et seq.) is arecognized method for determining surface area. BET surface area ofsilicas generally is less than 450 m²/g, and useful ranges of surfaceinclude from ˜32 to ˜400 m²/g, ˜100 to ˜250 m²/g, and ˜150 to ˜220 m²/g.

The pH of the silica filler is generally from ˜5 to ˜7 or slightly over,preferably from ˜5.5 to ˜6.8.

Some commercially available silicas which may be used include Hi-Sil™215, Hi-Sil™ 233, and Hi-Sil™ 190 (PPG Industries, Inc.; Pittsburgh,Pa.). Other suppliers of commercially available silica include GraceDavison (Baltimore, Md.), Degussa Corp. (Parsippany, N.J.), RhodiaSilica Systems (Cranbury, N.J.), and J.M. Huber Corp. (Edison, N.J.).

Silica can be employed in the amount of ˜1 to ˜100 phr, preferably in anamount from ˜5 to ˜80 phr. The useful upper range is limited by the highviscosity that such fillers can impart.

Other useful fillers include all forms of carbon black including, butnot limited to, furnace black, channel blacks and lamp blacks. Morespecifically, examples of the carbon blacks include super abrasionfurnace blacks, high abrasion furnace blacks, fast extrusion furnaceblacks, fine furnace blacks, intermediate super abrasion furnace blacks,semi-reinforcing furnace blacks, medium processing channel blacks, hardprocessing channel blacks, conducting channel blacks, and acetyleneblacks; mixtures of two or more of these can be used. Carbon blackshaving a surface area (EMSA) of at least 20 m²/g, preferably at least˜35 m²/g, are preferred; surface area values can be determined by ASTMD-1765 using the CTAB technique. The carbon blacks may be in pelletizedform or an unpelletized flocculent mass, although unpelletized carbonblack can be preferred for use in certain mixers.

The amount of carbon black can be up to ˜50 phr, with ˜5 to ˜40 phrbeing typical. When carbon black is used with silica, the amount ofsilica can be decreased to as low as ˜1 phr; as the amount of silicadecreases, lesser amounts of the processing aids, plus silane if any,can be employed.

Elastomeric compounds typically are filled to a volume fraction, whichis the total volume of filler(s) added divided by the total volume ofthe elastomeric stock, of ˜25%; accordingly, typical (combined) amountsof reinforcing fillers, i.e., silica and carbon black, is ˜30 to 100phr.

When silica is employed as a reinforcing filler, addition of a couplingagent such as a silane is customary so as to ensure good mixing in, andinteraction with, the elastomer(s). Generally, the amount of silane thatis added ranges between ˜4 and 20%, based on the weight of silica fillerpresent in the elastomeric compound.

Coupling agents can have a general formula of A-T-G, in which Arepresents a functional group capable of bonding physically and/orchemically with a group on the surface of the silica filler (e.g.,surface silanol groups); T represents a hydrocarbon group linkage; and Grepresents a functional group capable of bonding with the elastomer(e.g., via a sulfur-containing linkage). Such coupling agents includeorganosilanes, in particular polysulfurized alkoxysilanes (see, e.g.,U.S. Pat. Nos. 3,873,489, 3,978,103, 3,997,581, 4,002,594, 5,580,919,5,583,245, 5,663,396, 5,684,171, 5,684,172, 5,696,197, etc.) orpolyorganosiloxanes bearing the G and A functionalities mentioned above.An exemplary coupling agent isbis[3-(triethoxysilyl)propyl]tetrasulfide.

Addition of a processing aid can be used to reduce the amount of silaneemployed. See, e.g., U.S. Pat. No. 6,525,118 for a description of fattyacid esters of sugars used as processing aids. Additional fillers usefulas processing aids include, but are not limited to, mineral fillers,such as clay (hydrous aluminum silicate), talc (hydrous magnesiumsilicate), and mica as well as non-mineral fillers such as urea andsodium sulfate. Preferred micas contain principally alumina, silica andpotash, although other variants also can be useful. The additionalfillers can be utilized in an amount of up to ˜40 phr, typically up to˜20 phr.

Other conventional rubber additives also can be added. These include,for example, process oils, plasticizers, anti-degradants such asantioxidants and antiozonants, curing agents and the like.

All of the ingredients can be mixed using standard equipment such as,e.g., Banbury or Brabender mixers. Typically, mixing occurs in two ormore stages. During the first stage (often referred to as themasterbatch stage), mixing typically is begun at temperatures of ˜120°to ˜130° C. and increases until a so-called drop temperature, typically˜165° C., is reached.

Where a formulation includes silica, a separate re-mill stage often isemployed for separate addition of the silane component(s). This stageoften is performed at temperatures similar to, although often slightlylower than, those employed in the masterbatch stage, i.e., ramping from˜90° C. to a drop temperature of ˜150° C.

Reinforced rubber compounds conventionally are cured with ˜0.2 to ˜5 phrof one or more known vulcanizing agents such as, for example, sulfur orperoxide-based curing systems. For a general disclosure of suitablevulcanizing agents, the interested reader is directed to an overviewsuch as that provided in Kirk-Othmer, Encyclopedia of Chem. Tech., 3ded., (Wiley Interscience, New York, 1982), vol. 20, pp. 365-468.Vulcanizing agents, accelerators, etc., are added at a final mixingstage. To ensure that onset of vulcanization does not occur prematurely,this mixing step often is done at lower temperatures, e.g., starting at˜60° to ˜65° C. and not going higher than ˜105° to ˜110° C.

The following non-limiting, illustrative examples provide the readerwith detailed conditions and materials that can be useful in thepractice of the present invention.

EXAMPLES Example 1 Nd Complex

A mixture of 59 mg NaH (2.44 mmol) and 600 mgN,N′-bis(3,5-di-tert-butyl-salicylidene)ethylenediamine (1.22 mmol) in12 mL THF was refluxed for ˜40 minutes. To the resulting yellow solutionwas added 481 mg NdCl₃(THF)₂ (1.22 mmol), and this mixture was refluxedfor ˜6 hours.

The reaction mixture was filtered through diatomaceous earth, with thefilter cake being washed with THF. The combined filtrates wereevaporated under vacuum to give 880 mg of a lemon-yellow solid havingthe following structure:

Examples 2-6 Polybutadienes

To a N₂-purged dry bottle was added 0.96 mL of 1,3-butadiene in hexane(21.2%), 8.4 mL toluene, 2.9 mL MAO (4.32 M in toluene), and 92 mg ofthe Nd complex from Example 1, followed by 2.6 mL diisobutylaluminumhydride (DIBAH, 1.0 M in hexane). This catalyst composition (0.0083 MNd) was aged at room temperature for ˜20 minutes before use below.

To five N₂-purged dry bottles with self-sealing rubber lines andperforated metal caps were added 97 g hexane and 236 g 1,3-butadienesolution (21.2% in hexane). The following amounts of the catalystsolution from the preceding paragraph were added to the bottles (withthe parenthetical number being the resulting amount of Nd complex):

-   -   Ex. 2—1.8 mL (0.030 mmol)    -   Ex. 3—2.1 mL (0.035 mmol)    -   Ex. 4—2.4 mL (0.040 mmol)    -   Ex. 5—2.7 mL (0.045 mmol)    -   Ex. 6—3.0 mL (0.050 mmol)

Each bottle was tumbled in a 65° C. water bath for ˜60 minutes. Eachpolymer cement was quenched with 3 mL isopropanol containing 12% (bywt.) BHT before being coagulated in 2 L isopropanol containing 0.5 gBHT. The resulting polymers were drum-dried.

The properties of these polymers are summarized in the following table,with the molecular weight data and microstructure data being determinedby, respectively, GPC and FTIR. Mooney viscosity (ML₁₊₄) values weredetermined with an Alpha Technologies™ Mooney viscometer (large rotor)using a one-minute warm-up time and a four-minute running time.

TABLE 1 Properties of polymers from Examples 2-6 2 3 4 5 6 polymeryield, % 92.8 94.8 95.4 96.2 96.6 ML₁₊₄ @ 100° C. 47.4 37.6 30.8 25.020.5 cis BD mer, mol % 94.7 93.3 91.8 90.7 89.7 trans BD mer, mol % 4.86.1 7.6 8.7 9.7 1,2-vinyl BD mer, mol % 0.6 0.6 0.6 0.6 0.6 M_(n)(kg/mol) 140.1 — — — — M_(w)/M_(n) 1.90 — — — —

Example 7 Copolymer

To a N₂-purged dry bottle was added 0.77 mL of 1,3-butadiene in hexane(21.5%), 6.8 mL toluene, 2.3 mL MAO (4.32 M in toluene), and 75 mg ofthe Nd complex from Example 1, followed by 2.1 mL DIBAH (1.0 M inhexane). This catalyst composition (0.0083 M Nd) was aged at roomtemperature for ˜20 minutes before use below.

To a dry 3.8 L reactor purged with ethylene was charged 816 g hexane and1.12 kg 1,3-butadiene solution (21.5% in hexane); this reactor waspressurized to 0.2 MPa with ethylene. The catalyst composition from thepreceding paragraph was charged into the reactor, the reactor waspressurized to 1.7 MPa with ethylene, and the reactor jacket temperaturewas set to 66° C. Polymerization was allowed to proceed for ˜4 hours.

The polymer cement was cooled and coagulated with 10 L isopropanolcontaining 4 g BHT, with the resulting polymers being drum-dried.

The amount of polymer recovered was 47.7 g. As determined by ¹H NMR, thepolymer contained ˜3.2 mole percent ethylene mer. The butadiene merincorporated almost essentially completely in 1,4-form, i.e., the vinylcontent was ˜0.7 mole percent. The M_(n) of the polymer was 195,000Daltons, and the M_(w)/M_(n) was ˜2.42.

The foregoing examples have employed ethylene as an exemplary olefin and1,3-butadiene as an exemplary polyene. These choices were made in viewof a variety of factors including cost, availability and ability tohandle. From the foregoing examples employing these materials, theordinarily skilled artisan will be able to extend these examples to avariety of homo- and interpolymers.

That which is claimed is:
 1. A catalyst composition comprising acatalyst activator and a lanthanide metal complex of the general formula

where M represents a Nd or Gd atom; L represents a neutral Lewis base; zis an integer of from 0 to 2 inclusive, with the proviso that each L isthe same when z is 2; R¹ is a divalent atom or group that contains atleast one C,O,S,N,P,Si,Se,Sn or B; each R² independently is H, a halogenatom, substituted or unsubstituted hydrocarbyl group, the radical of aheterocyclic compound, or a heteroatom-containing group; and R³ is ahalogen containing group, a group that contains an Al atom, or R², withthe proviso that (1) two R² groups together with the atoms to which eachis bonded can form a ring structure, (2) one R² group and R¹ R³ togetherwith the atoms to which each is bonded can form a ring structure, and/or(3) R¹ and R³ together with the atoms to which each is bonded can form aring structure.
 2. The catalyst composition of claim 1 wherein L istetrahydrofuran.
 3. The catalyst composition of claim 1 wherein R³ is ahalogen atom.
 4. The lanthanide metal complex of claim 1 wherein z is 1.5. The catalyst composition of claim 1 wherein said catalyst activatorcomprises an alkylating agent.
 6. The catalyst composition of claim 1wherein said catalyst activator comprises a non-coordinating anion. 7.The catalyst composition of claim 1 wherein said catalyst activatorcomprises a non-coordinating anion precursor.
 8. The catalystcomposition of claim 1 wherein said catalyst activator comprises (1) analkylating agent that is an organoaluminum compound or anorganomagnesium compound and (2) a non-coordinating anion or anon-coordinating anion precursor, L represents tertahydrofuran , and R³represents a halogen atom.
 9. A process for providing a polymer, saidprocess comprising contacting one or more ethylenically unsaturatedhydrocarbon monomers with the catalyst composition of claim 1, therebyproviding said polymer.
 10. The process of claim 9 wherein said one ormore ethylenically unsaturated hydrocarbon monomers comprises at leastone type of polyene.
 11. The process of claim 10 wherein said at leastone type of polyene comprises one or more conjugated dienes.
 12. Theprocess of claim 10 wherein said one or more ethylenically unsaturatedhydrocarbon monomers further comprises at least one type of α-olefin.13. The process of claim 12 wherein said at least one type of α-olefincomprises ethylene.
 14. The process of claim 13 wherein said contactingoccurs in a solvent system that comprises a C₅-C₁₂ aliphatic alkane. 15.The process of claim 14 wherein said solvent system comprises hexane.16. The process of claim 15 wherein said polymer comprises about 3 molepercent ethylene.
 17. The process of claim 15 wherein said polymercomprises less than 1 mole percent of conjugated diene mer in a vinylconfiguration.
 18. The process of claim 9 further comprising reactingsaid polymer with a functionalizing agent so as to provide terminalfunctionality to said polymer.